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Feedback Speed Control. Embedded Systems Interfacing. Overview. Background Task 1 MATLAB ® Step Response Root Locus Task 2 Scaled Coefficients Task 3 Proportional-Integral Speed Control Task 4 Step Response for: Critically Damped Over Damped Under Damped. PWM/Motor Speed Labs. +12 VDC.
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Feedback Speed Control Embedded Systems Interfacing
Overview • Background • Task 1 MATLAB® Step Response Root Locus • Task 2 Scaled Coefficients • Task 3 Proportional-Integral Speed Control • Task 4 Step Response for: • Critically Damped • Over Damped • Under Damped
PWM/Motor Speed Labs +12 VDC +5 VDC +5 VDC LM2907 PIC24FJ128 ADC PWM V(speed) TD62003AP
Open-Loop Load-Speed Characteristics Speed Load
Block Diagram Darlington Driver, Motor and Freq-to-Volt Internal To feedback.c PIC24FJ128
PID Controller PID • Time-Domain • Laplace-Domain of PI Controller
Stability • Control Ratio • Critically Damped
Task 1 – Step Response Analysis • Within MATLAB® • Define A and B • Define transfer Function • Use step()
Task 3 Within main( ) • Initialization • RD0 • Timer 3 • ADC Interrupts and Timer 3 Interrupt • PWM • ADC • PMP then LCD • LCD text on screen
Task 3 Within main( ) • Endless Loop • Wait for for semaphore == 1 • Clear semaphore • Calculate new output value using difference equation • Write to PWM • Update out(k+1), in(k+1), and in(k+2) • Display Speed
Task 3 Within Timer 3 ISR • Clear Interrupt flag • Start sampling
Task 3 Within ADC ISR • Get new speed reading and clear DONE • Set semaphore • Check for one-hundred passes (100 x 50ms = 5 s) • If 100 passes then • Toggle RD0 • Calculate new reference = Step*D0 + Offset • Reset pass count • Else • Increment pass count • Clear ADC interrupt flag
Task 3 • Download to project folder • feedback.c • peripherals.a (library archive) • peripherals.h • Create project and add all three files • Add linker script • Create heap
Open-Loop Load-Speed Characteristics Closed Loop Speed Open Loop Load
Task 4 • Use Internal Reference • Use MPLAB’s Data Monitor and Control Interface to Adjust K1 and K2 • Capture Image on MSO and repeat for • Critically Damped • Over Damped • Under Damped
DMCI Configuration Right Click
DMCI Use • Press Save after Dynamic Data Control is configured • Press Halt • Adjust Sliders • Use Mouse • Up arrow and Down arrow • Press Start